It's gone further than America at this point.
I was at my friends last night and he got a text from his girlfriend who was staying somewhere else in the country (which is the UK, btw) saying there was a small group of people dressed as clowns in the park across the road from the flat she was staying in.
She sent a picture message of them. There were quite a few of them.
I like to believe they were sharing trade secrets like how to make more complex balloon animals and practicing their advanced custard pie throwing techniques.
...There's a big difference between "I would attack the person" and "I would attack the people". You've started with singular and ended with plural as though they're the exact same situation.
If it was just one person, I'd give 'em a punch...I mean, what's so unbelievable about that? The clown costume doesn't give them super powers or something.
If it was a group, well, duhhh. Of course you wouldn't attack a group of people, you're gonna do your best to avoid that unless you're either a genuine BAMF blackbelt or a moron. Being dressed as clowns has nothing to do with it, it's just that it's a group of people...They could be dressed as delicious friggin' blueberry muffin's, attacking group of people is stupid, we don't need Captain Obvious to tell us that.